LGTM configuration file (#1148)

* Adding LGTM config file

* LGTM update

lgtm.yml

@@ -0,0 +1,12 @@
+extraction:
+  cpp:
+    after_prepare:
+    - "export GCC=gcc-arm-none-eabi-9-2019-q4-major"
+    - "wget https://github.com/rusefi/build_support/raw/master/${GCC}-x86_64-linux.tar.xz -O compiler.tar.xz"
+    - "tar xf compiler.tar.xz -C ${LGTM_WORKSPACE}"
+    - "mv ${LGTM_WORKSPACE}/${GCC} ${LGTM_WORKSPACE}/gcc-arm"
+    index:
+      build_command:
+      - "export PATH=${LGTM_WORKSPACE}/gcc-arm/bin:${PATH}"
+      - "cd firmware"
+      - "make -j $(nproc) PROJECT_BOARD=microrusefi PROJECT_CPU=ARCH_STM32F4"